Do naps affect night sleep? They can, but it depends almost entirely on how long the nap is and when you take it. A twenty-minute nap at 1.30pm will not harm most people's night. A ninety-minute nap at 5pm almost certainly will. The difference comes down to sleep pressure, which is the key to napping well.
If you have insomnia, the honest advice is different: naps are usually best avoided until the nights are sorted, because every minute of daytime sleep is a minute of pressure that will not be there at bedtime. For everyone else, a short nap is a perfectly good tool, provided you follow a couple of rules.
Sleep pressure: the thing a nap spends
From the moment you wake, a chemical called adenosine builds up in the brain, and with it the feeling of needing sleep. By evening the pressure is high enough that you drop off easily. Sleep clears the adenosine; that is partly what sleep is for.
A nap clears some of it too. A short nap releases a little, and the pressure has the rest of the day to rebuild. A long or late nap releases a lot with little time to recover, and you arrive at bedtime with a half-empty tank: you lie awake, sleep late, wake tired, need a nap, and the cycle repeats. People who say "naps ruin my sleep" are usually right about their naps and wrong about naps in general.
In short: A nap spends sleep pressure. Spend a little, early, and it is repaid by bedtime. Spend a lot, late, and the night pays for it.
The twenty-minute guideline
Somewhere between ten and twenty minutes is the sweet spot for most people. In that window you get light sleep, which is enough to improve alertness, mood and concentration for a few hours, without going into deep sleep. Waking from deep sleep produces the heavy, disorientated feeling that can last half an hour or more and makes some people swear off naps. Keep the nap short and you avoid it.
Set an alarm for 25 minutes to allow time to drop off. If you are still awake when it goes off, that is fine: quiet rest with your eyes closed has some benefit, and it tells you that you were not as tired as you thought.
The exception is the full-cycle nap of around 90 minutes, which takes you through deep sleep and out the other side. It can make sense after a night shift or a bad night with a baby, but it is not an everyday habit if you also want a full night.
Timing: early afternoon, then stop
Most people have a natural dip in alertness between about 1pm and 3pm, which is why the post-lunch slump feels the way it does. That is the ideal nap window, and it is far enough from bedtime for the pressure to rebuild.
After about 3pm, the cost rises. A nap at 4 or 5pm, even a short one, makes it harder to fall asleep at 11 for most people. The sofa doze at 8pm while watching television is the worst of all, because it sits in exactly the hours when sleep pressure should be peaking. If you regularly fall asleep on the sofa and then lie awake in bed, that doze is the likely reason, and our guide to how to sleep when you're not tired has more on what to do instead.
Who should avoid naps
People with insomnia. If you struggle to fall or stay asleep at night, daytime sleep works against you. Building sleep pressure through the day is one of the main tools of CBT-I, the recommended treatment for insomnia, and naps undo it. Once the nights are reliable, a short nap becomes fine again.
Anyone who feels worse afterwards. Some people simply do not nap well and wake grumpier than they started. There is no rule that says you must.
If you need a nap every day to get through, or you sleep seven or eight hours and are still exhausted by the afternoon, that is worth looking at rather than papering over. Our guide to why you feel tired but can't sleep covers the common reasons, and persistent daytime sleepiness is a reasonable thing to raise with a GP.
Napping well: the practical bit
- Set an alarm for 20 to 25 minutes.
- Lie down if you can, somewhere cool and quiet, but not necessarily in bed. If your nights are poor, keeping the bed for night sleep helps.
- Deal with light. Daytime naps happen in daylight, and a bright room makes light sleep lighter still. Closing curtains works; a sleep mask works anywhere, including on a train or in a car on your lunch break. Our guide to choosing a sleep mask covers the types.
For napping in daylight
A mask turns a bright afternoon into a dark enough room, wherever you happen to be.
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Contoured (3D) sleep mask
Example: Manta Sleep Mask
A contoured mask has raised eye cups so the fabric does not press on your eyelids, which many people find more comfortable and which allows the eyes to move freely in REM sleep. Manta's version is marketed with adjustable eye cups and a wide, flat strap designed to reduce light leaks.
- Best for
- Side sleepers and anyone who dislikes pressure on the eyes
- Key feature
- Moulded eye cups that sit around, not on, the eyes
- Why it may help
- The main failure of a cheap flat mask is light leaking in around the nose. A contoured design with an adjustable strap closes that gap for more face shapes.
- Worth knowing
- Bulkier than a flat mask, so less convenient for travel.
Silk sleep mask
Example: Mulberry silk eye masks (various brands)
Flat masks made from mulberry silk are marketed for comfort and breathability and are light enough to pack easily. They rely on a soft fit rather than eye cups.
- Best for
- Comfort against the skin, warm sleepers, travel
- Key feature
- Lightweight, breathable, cool-feeling fabric
- Why it may help
- If you find fabric on the eyelids fine and simply want something light and cool, silk is a comfortable option, though flat masks tend to leak more light around the nose than contoured ones.
- Worth knowing
- Less light-blocking at the edges than a contoured mask; hand-wash care.
The coffee nap, honestly
The idea is to drink a coffee and then immediately nap for fifteen to twenty minutes. Caffeine takes around twenty minutes to start working, so it kicks in as you wake, and the nap has cleared some of the adenosine that caffeine blocks. A small number of studies, mostly on tired drivers, found the combination reduced sleepiness more than either alone.
It works as a daytime trick, particularly before a long drive. Its limit is the same as any afternoon coffee: use it before 2pm or not at all, and see caffeine and sleep for why.
The short version
If your nights are fine, nap if you enjoy it: twenty minutes, before 3pm, with an alarm. If your nights are not fine, skip naps for a few weeks and let the pressure build. Either way, the 8pm sofa doze is the one to lose. There is more on daytime habits in the Sleep Habits guides.
Frequently asked questions
How long should a nap be?
About ten to twenty minutes if you want to wake refreshed and get on with the day. Longer naps drift into deep sleep, and waking from that leaves you groggy for a while. A full 90-minute nap covers a whole sleep cycle and avoids the grogginess, but it takes a large bite out of the night's sleep pressure.
What is the best time of day to nap?
Early afternoon, roughly 1pm to 3pm, when there is a natural dip in alertness. It is far enough from bedtime that the sleep pressure will rebuild. Napping after about 3pm or 4pm makes it harder to fall asleep that night for most people.
Is it bad to nap every day?
Not in itself. A short daily nap is normal in many cultures and harmless for most people. If you find you need a long nap every day to function, that is worth looking at: it can mean the night's sleep is not doing its job, which is worth mentioning to a GP if it persists.
Does a coffee nap really work?
There is some evidence for it. Drinking a coffee and then immediately napping for 15 to 20 minutes means the caffeine starts working about as you wake, and a small number of studies, mainly in drivers, found the combination reduced sleepiness more than either alone. It is a daytime trick, not something to use in the afternoon if you want to sleep that night.
Sources and further reading
- NHS: Sleep and tiredness
- Sleep Foundation: Napping
- NHS: Insomnia
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Written and reviewed by the Quiet Mind Sleep editorial team in line with our editorial policy. Spotted an error? Let us know.
